This invention relates to magnetic head assemblies for use in conjunction with magnetic contact recording media.
Magnetic head assemblies typically contain one or more raised strips or supports which have surfaces over which the magnetic recording media passes. Embedded in each support surface is a transducer which may be a recording transducer (i.e. recording or writing head) for writing information (i.e., bits of data) onto the media or a reproducing transducer (i.e., reproducing or reading head) for reading information from the media. An embedded recording transducer produces a magnetic field in the vicinity of a small gap in the core of the recording transducer which causes information to be stored on the magnetic media as it streams across the support surface. In contrast, a reproducing transducer detects a magnetic field near the surface of the magnetic media in the vicinity of a small gap as the media streams over the support surface.
There is typically some microscopic separation between the gap of the transducer core and the recording media. This separation reduces the magnetic field coupling between the recording transducer and the media during writing and between the media and the reproducing transducer during reading. The magnetic field coupling is proportional to e.sup.-kd.lambda., where d is the head-to-media separation, .lambda. is the recording wavelength, and k is a constant. The magnetic field coupling decreases exponentially both with respect to increases in the separation between the media and the support and with respect to increases in the recording density. The amount of media area required to store a bit of data is one factor in determining recording density and the recording wavelength .lambda.. As less media area is required to store a bit of data, the recording density increases and inversely, the recording wavelength .lambda. decreases. Thus, a limited amount of head-to-media separation may be acceptable at low recording densities, such as 10-20 KFCI, where the recording wavelength .lambda. is large enough to provide sufficient magnetic coupling. However, at higher densities, such as 40-80 KFCI, substantially no head-to-media separation can be tolerated or the magnetic coupling will be insufficient.
During operation when the magnetic media is magnetic recording tape, a uniform tension is applied to the tape as the tape passes at a wrap angle around a support and transducer core surface having a uniform height and a uniform width. It is desirable to keep the tape in intimate contact with the transducer core, and specifically, in contact with a gap in the core, and thus, minimize "spacing loss".
The tape exerts a pressure against the support surface that is uniform along a longitudinal axis of the support. The pressure is essentially proportional to the tension and the wrap angle and inversely proportional to the support width. In this regard, increased pressure reduces "spacing loss".
Tape pressure against the support surface can be modified. For example, the pressure can be changed by modifying the tension in the tape, by modifying the wrap angle of the tape on the support surface, or by modifying the width of the support surface. Accordingly, pressure on the support surface can be increased by increasing the tension in the tape, by increasing the wrap angle of the tape on the support surface, or by decreasing the width of the support surface.
However, increased pressure has negative consequences. For example, increased pressure reduces tape life and increases the possibility of tape damage and data loss. Additionally, increased pressure causes the support surface to wear down more quickly which results in a shorted head life. Moreover, increased pressure can result in uneven wear along the support surface. Uneven wear can be particularly troublesome between regions of the support with the transducer and without the transducer where depressions may be formed in the support surface which may make spacing loss unavoidable.